Involvement of TRPV1 in bone cancer pain : development of novel strategies for treating cancer pain

1.ET-1与TRPV1的相互作用以前的研究表明，ETA拮抗剂可以减轻骨癌疼痛，但其机制尚不清楚。然而，ET-1的伤害性作用机制尚未完全阐明。在这项研究中，我们用膜片钳和行为学分析研究了ET-1和TRPV1的功能相互作用。在电压钳实验中，TRPV1对辣椒素、热和质子的反应被ET-1以PKC依赖的方式敏化。Western印迹分析显示，在表达TRPV1和ETA的HEK293细胞中，ET-1可诱导TRPV1的磷酸化。在DRG神经元中也观察到ET-1诱导的辣椒素反应的增强。在行为学分析中，在缺乏TRPV1的小鼠中，ET-1诱导的热痛觉过敏被取消。这些发现表明，TRPV1是参与ET-1诱导的痛觉过敏的一个重要分子。2.骨癌增加di…中瞬时受体潜伏期Vanilloid亚家族1的表达背根神经节神经元的更多亚群我们用强大的TRPV1拮抗剂5-IODORESiniferatoxin(I-RTX)评价了药物阻断TRPV1的镇痛效果，并检测了骨癌是否改变了TRPV1在骨癌痛小鼠初级感觉神经元中的表达和分布。与赋形剂相比，I-RTX腹膜腔给药可显著减轻骨癌相关疼痛行为。Western印迹和RT-PCR分析表明，在肉瘤种植同侧DRG中，TRPV1的表达水平显著升高。免疫组织化学分析表明，骨肉瘤移植不仅使DRG神经元中TRPV1阳性神经元的百分比增加，而且使轮廓的分布整体右移。共定位研究表明，与假手术组相比，移植骨肉瘤小鼠背根神经节神经元中TRPV1与NF200和CGRP共定位的百分比增加，而与IB4不共定位的百分比增加。综上所述，TRPV1激活在骨癌疼痛的发生中起关键作用，而骨癌增加了DRG神经元不同亚群中TRPV1的表达。这些发现可能会为骨癌疼痛的治疗提供新的策略。较少

1.Interaction of ET-1 with TRPV1The previous study showed that an ETA antagonist decreased bone cancer pain, but its mechanisms have been unclear. However, the mechanisms of the nociceptive action of ET-1 have not been fully elucidated. In this study, we examined the functional interaction of ET-1 with TRPV1 using patch clamp and behavioral analyses. In voltage-clamp experiments, the responses of TRPV1 to capsaicin, heat and proton were sensitized in the presence of ET-1 in a PKC-dependent manner. Western blot analysis revealed that ET-1 evoked phosphorylation of TRPV1 in HEK293 cells expressing TRPV1 and ETA. ET-1-induced potentiation of responses to capsaicin was also observed in DRG neurons. In behavioral analyses, ET-1-induced thermal hyperalgesia was abolished in mice lacking TRPV1. These findings indicate that TRPV1 is an important molecule that is involved in ET-1-induced hyperalgesia.2.Bone cancer increases transient receptor potential vanilloid subfamily 1 expression within di … More stinct subpopulations of dorsal root ganglion neuronsWe evaluated the analgesic effects of pharmacological blockade of TRPV1 using the potent TRPV1 antagonist 5-iodoresiniferatoxin (I-RTX) and examined whether bone cancer can change TRPV1 expression and distribution in the primary sensory neurons in a mouse model of bone cancer pain. The bone cancer-related pain behaviors were significantly reduced by intraperitoneal administration of I-RTX, compared to vehicle. Western blot and RT-PCR analyses revealed that TRPV1 level was significantly increased in DRGs ipsilateral to sarcoma implantation. Immunohistochemical analysis showed that implantation of osteosarcoma induced not only an increase in the percentage of TRPV1-positive neurons among DRG neurons but also an overall shift in the d stribution of area of profiles to the right. Colocalization study showed that the percentages of colocalization of TRPV1 with NF200 and CGRP but not IB4 among DRG neurons in mice with oseteosarcoma implantation were increased compared to those in sham mice. In conclusion, TRPV1 activation plays a critical role in the generation of bone cancer pain, and bone cancer increases TRPV1 expression within distinct subpopulation of DRG neurons.These findings may lead to novel strategies for the treatment of bone cancer pain. Less